Most electro-mechanical equipment, such as, computers, image processing equipment, and the like, employ some sort of heat exchanger to transfer fluid (heat) from one or more component parts to an alternative fluid stream. Since heat build-up generally diminishes the long-term performance and reliability of component parts of such equipment, heat exchanges are generally used to facilitate the heat transfer process.
In image processing equipment, for instance, a thermal write head element is heated, either by lasers or some other source, during operations (see, for instance, commonly owned U.S. Pat. No. 5,268,708 hereby incorporated herein by reference). During a work cycle, the write head element will absorb an enormous amount of heat. An overheated write head element may ultimately result in premature diminished print quality which would require equipment maintenance, typically write head element changeover or cleaning. Natural convection heat exchangers are most widely used to transfer heat away from the write head element. A shortcoming of naturally cooled heat sinks is that they typically require enormous space or volume within the equipment environment. Typically, natural convected cooled heat sinks require up to an order of magnitude increase in fin area to achieve comparable performance with that of a forced convected cooled heat sink.
Forced convective heat exchangers which employ oversized fans to increase the air flow at the heat sink have also been used to facilitate heat transfer from the write head element of image processing equipment. Existing forced convective heat exchangers, however, involve the use of relatively low flow air moving means (or fans) which are limited to overcoming only minimal static pressure in the heat sink. Moreover, the aforementioned forced convective heat exchangers are generally limited in the amount of fin surface area that can be provided for any given heat sink volume, due to the limited static pressure capability of the fin.
Conventional tubeaxial fans directly mounted to a heat sink may well be a option for cooling the write head element of image processing equipment. However, it is well known that tubeaxial fans are limited in their ability to overcome any appreciable resistance to airflow. By increasing the fin surface area increases the airflow resistance that the tubeaxial fan must overcome. At some point, increasing the surface area will decrease heat sink performance, as the tubeaxial fan becomes the limiting factor in the amount of air flow resistance it can overcome. Thus, for a given heat sink volume, there is a limit to the thermal resistance that a direct mounted existing tubeaxial fan can provide
Moreover, remote mounted blowers may also be used in conjunction with the heat sink. However, it is our experience that remote mounted blowers have the inherent disadvantage of not offering a compact solution because of size and power that they require to function independent from the rest of the system. Additionally, remote mounted blowers may cause undesired disturbances in the translation of the write head element due to the ducting; thus, causing image defects. Where compact systems are required, these remote blowers are not a viable option.
Therefore, there persists a need for image processing equipment with an improved heat exchanger to facilitate heat transfer away from the write head element that has a compact, high velocity air moving means which can overcome high static pressure in very large surface area heat sinks.